The invention concerns a construction set for the erection of a supporting structure.
A supporting structure of the abovementioned type is known (DE-GM 83 30 969), is used for the erection of a supporting structure. In the known construction set a spherical connecting joint provided with four outer surfaces set an angle of 90.degree. to each other, wherein in each of the surfaces a slot open to one side is located, the slots expanding inwardly in a shape of a T. Into these open slots suspension heads adapted to the profile of the T groove may be inserted, the suspension heads being mounted on the frontal sides of supporting beams.
The connecting joint has a center threading whereby it may be inserted by means of threaded bolts provided in suspension tubes extending flush with the threading. Following the insertion of the suspension heads of the vertical support beams, a closure disk is provided to hold the suspension heads by means of an intermediate piece also acting as fastening means to rotate the threaded bolts, when the connecting joint is screwed to the associated vertical suspension tubes. The supporting structures erected in this manner may consist only of vertical and horizontal beams perpendicular to each other. The assembly of such a structure is time consuming in view of the necessary screwing operations. Furthermore, the overall layout is expensive because of the numerous parts needed and their mutual mounting.
Another joint connection for structures assembled from rods is also known (DE-OS 24 57 674); it makes it possible to erect supporting structures for skeleton type constructions; is does not consist only of rods mounted perpendicularly to each other. In this configuration an element in the form of a hollow hemisphere is provided as the connecting joint, in which slots extending along large circles are located, into which the ends of supporting rods equipped with appropriate threaded pins and nuts or threaded heads may be inserted at different angles. With such connecting joints it is thus possible to erect tetrahedral or cubic base elements for supporting structures, assembled from a plurality of such base elements. However, in supporting structures of this type initially the manufacture of the necessary structural elements is relatively expensive; assembly is cumbersome and requires either that the inside of the hemisphere serving as the connecting joint be accessible for the insertion of the threaded heads or nuts, or that measures are taken to prevent the subsequent rotation of the support tubes, when the latter are moved with locking bar like heads behind the slots. The assembly of such a system is time consuming and complicated in view of the necessary screwing operation for each supporting rod.
Finally, regulations are known (Deutsche Bauzeitung, No. 3, 1967, p. 226), wherein the flattened ends of tube like rods made of aluminum, but for reasons of mechanical strength preferably of steel, are provided with notches and pressed axially and positively into the corresponding slots of a connecting joint. Assembly is expensive because of the clamped joint desired. Depending on the application, different extruded connecting joints and corresponding rods must be provided.